This invention relates to the art of furnace filters, and more particularly to filter assemblies utilizing bulk filter media instead of individual replacement filters.
Filters of one type or another are installed on commercial and residential furnaces all over the country. Many of these furnaces employ a traditional replacement filter consisting of a rectangular sheet of filter media encased in a cardboard frame which provides support to the filter media. This type of filter is generally housed in a filter support structure which is built into the air intake of the furnace. The filter normally covers the entire opening of the air intake, giving the traditional replacement filters substantial size in both length and width. To replace such a filter, the old filter must first be manually removed and disposed of, and then a replacement filter can be inserted into the filter support structure. Since the function of these filters is to trap dirt and other particulate material, thereby removing the contaminants from the air, these filters naturally become clogged with dust and dirt. At this point, the filter becomes ineffective as it no longer has the ability to remove a significant amount of dirt and dust particles from the air. The filter also becomes inefficient as the dirt in the filter reduces the filter""s ability to pass air. This requires the furnace motor to work harder to get the necessary amount of air through the furnace. Only by frequent replacement of the filter does the air continue to be efficiently and effectively cleaned.
There are inconveniences associated with such frequent replacement of these filters. First, since the dirty replacement filters must be manually removed and disposed of, the person servicing the furnace is required to physically handle the dirty filters. The filters must be handled carefully to avoid shaking the dust and dirt out of the filter and into the furnace or the surrounding area. This is made more difficult due to the size of the filter. These filters are typically not heavy, but often require two hands to handle carefully. Second, to ensure effectiveness and efficiency, the traditional replacement filter must be continually monitored to determine when the filter should be changed. Unfortunately, there is no reliable indicator to suggest when the filter needs to be replaced. So the filters are not necessarily replaced at the optimum time, instead being thrown out with useable life remaining or, worse, being used while inefficient and ineffective. Third, replacement filters of the foregoing character only provide primary filtration at the furnace intake. Once the air is forced through the furnace and into the duct work, the filter at the intake can provide no further filtration. In many situations, additional or supplemental filtration may be desired. However, the traditional type of replacement filter discussed above does not function in such a manner. Finally, the size of the traditional replacement filter, as discussed earlier, presents another inconvenient aspect of this type of filter. To be able to replace the filters as often as is necessary and to avoid making frequent trips to the hardware store to purchase a single filter, these traditional replacement filters are often purchased in quantity. However, due to their size, a quantity of these filters takes up a significant amount of valuable and often limited storage space.
U.S. Pat. No 4,174,205 to Koushiafes, the disclosure of which is incorporated herein by reference for background purposes, discloses a furnace air filter unit which includes a structure for supporting a bulk roll of filter material. The filter unit is supported in a furnace in the manner of the traditional filters discussed above, and the filter material can be manually pulled through the support structure so that a new segment replaces the dirty filter media. The manual indexing of the filter media would occur with the same frequency as discussed above with replaceable filter inserts and the dirty portion of the media is manually separated from the fresh filter media and disposed of. A serrated knife edge is used to cut the dirty filter material from the fresh segment. In all, the service person manually feeds the dirty filter media out of the support structure and then grasps the dirty filter material by hand, manually tears the material using the knife edge, and discards the dirty segment.
The Koushiafes"" filter unit may in part resolve the storage issue discussed above, but does not resolve the first three problems presented. In fact, the arrangement disclosed in Koushiafes may aggravate the problem associated with handling the dirty filter. In this respect, Koushiafes still requires the handling of dirty filter media, and also requires that the unsupported filter media be cut using a serrated edge. This will cause much of the dust and dirt from the filter media to shake loose and contaminate the area around the furnace intake. Furthermore, Koushiafes does not solve the issue of determining when to advance the filter media. Accordingly, the filter media may be discarded before being fully used, or it may be discarded after becoming inefficient and ineffective.
U.S. Pat. No. 5,599,363 to Percy, the disclosure of which is incorporated herein by reference for background purposes, discloses a vacuum filter belt apparatus such as for the air intake of a truck. The Percy apparatus is built as a complete structural unit, including permanent filter pad units, and while the unit includes a storage canister and a take-up canister the latter are mounted directly onto the body of the apparatus. A pressure responsive drive motor control provides for advancing the filter belt when it becomes dirty, and a belt depletion signal is provided. However, the unitary construction precludes the selection and separate mounting of the canisters and filter media support, respectively on, and in a furnace duct.
The present invention provides a furnace filter system having distinct advantages and improvements over the traditional furnace filter and the other prior art discussed above. As further explained in the following discussion, the present invention resolves or minimizes the shortcomings of traditional furnace filters in that it provides selectivity with respect to the location of mounting, selectivity with respect to orientation of the component parts relative to one another and a furnace duct, and ease and simplicity with respect to the installation thereof. Once mounted, the filter system minimizes the handling of dirty filters, eliminates the need for constantly monitoring the filter media""s effectiveness and efficiency, adds versatility with respect to controlling usage of the filter media, makes the storage space ordinarily required to store a quantity of individual replacement filters available for other purposes, and provides the ability for adding secondary or supplemental filtration to an existing filter system.
More particularly with regard to the foregoing attributes, a furnace filter system according to the invention includes individual structural components selectively mountable on a furnace duct to provide a supply roll of filter media on one side of a furnace duct for feeding filter media across the duct to the opposite side, where the used filter media is coiled and stored on a take-up roll mounted on the other side. When the entire supply roll is exhausted and wound onto the take-up roll, the latter is disposed of. A furnace filter system according to the invention also has the ability to selectively control displacement of the media from the storage roll to the take-up roll. In this regard the system can monitor the effectivity of the section of filter media extending across the duct and, upon reaching a pre-set level of ineffectiveness, the furnace filter system will index the filter media so that a new segment of filter media is extended across the duct. As the new filter media is advanced, the dirty portion is coiled and stored. Alternatively, the system can operate to advance the filter media based on lapsed time, or can be manually controlled. This is advantageous in that there may be situations where indexing over a time duration or on an as needed basis may more closely meet the requirements of the application and allow for a more efficient use of the filter media. Additionally, the furnace filter system preferably monitors the amount of filter media remaining in the supply and issues an alarm when a preselected amount of filter media remains. The number of times the furnace filter system can be indexed is only limited by the amount of bulk filter material on a supply roll. Therefore, the equivalent number of traditional filters the furnace filter system displaces is equal to the number of times the bulk roll can be indexed. Since the bulk roll only needs to be replaced once instead of the number of times traditional replacement filters would require, the furnace filter system results in significantly reduced maintenance and handling of dirty filter material.
Unlike the traditional furnace filter which is limited to mounting at the intake of the furnace, a furnace filter system according to the invention is suitable for installation at any number of different locations in a heating and ventilation system. Moreover, the system can be easily installed by a homeowner, or do-it-your-selfer, and accordingly is readily adapted to be provided in kit form for the latter purpose. The ease of installation is due to the simple and compact design of the system components, and the fact that the components can be mounted on a furnace duct with only a minor modification thereof. In this respect, the system includes a frame assembly designed to fit within the duct, and installation of the frame assembly only requires cutting slots in opposite sides of a duct to provide enough space to maneuver the frame into one of the slots. The supply roll assembly and the take-up roll assembly are independent of the frame and can be readily mounted along opposite sides of the duct adjacent the corresponding frame slot. The only mounting requirement is that the axes of the supply and take-up rolls be generally parallel to the front and sides of the frame assembly to optimize support and guidance of the filter media therebetween. The compact design and flexible mounting options also facilitate installation of the system in areas of limited clearance, such as a crawl space, and automatic advancement of the filter media advantageously minimizes the need to enter such areas of limited accessibility to monitor and replace the filter media. While the advantages of having a second filter in a ventilation system are well known, a filter system according to the present invention can also provide different levels of secondary filtration. That is, the filter system can utilize any one of a variety of types of filter media or combinations of filter media, thus optimizing the efficiency and effectiveness of the filtration. For example, a first filter system can be installed at the furnace intake with a roll of more coarse filter media for primary filtration, and/or another system can be installed downstream of the furnace with a roll of less coarse filter media for secondary filtration. Furthermore, the latter may be installed for use with a traditional filter at the intake. In either case the filter system will provide efficient and effective fluid filtration and is economical and convenient to operate and maintain.
It is accordingly an outstanding object of the present invention to provide a residential furnace filter system which minimizes the monitoring and maintenance required with respect to such systems heretofore available by utilizing bulk filter media which can be automatically advanced from a supply roll to a take-up roll in response to a given parameter to promote effective and efficient filtration and use of filter media.
Another object is to provide a furnace filter system of the foregoing character which is comprised of a minimum number of component parts and has a compact design and flexible mounting capabilities, thus making the system relatively simple to install and, therefore, adaptable for availability in kit form for installation on a furnace duct without disassembling the duct and with minimal modification of the duct structure.
Still another object is to provide a furnace filter system of the foregoing character which is structurally simple, thereby promoting the economic production of the system, and which facilitates easy insertion and removal of bulk filter media, without the need for tools, and with minimal handling of the bulk filter media.